Cam mechanism of knitting machines



J 4, 1956 .1. E. LYNAM ET AL CAM MECHANISM OF KNITTING MACHINES 5SheetsSheet 1 Filed March 4, 1952 Inventors: Term Eoumzo LYNRM8 BASILPoMERoV CAMPER Jan. 24, 1956 J. E. LYNAM ET AL CAM MECHANISM OF KNITTINGMACHINES 5 Sheets-Sheet 2 Filed March 4, 1952 Inventors; Tomy EDWARDLYNA Q, BAsIL PoMERoy COOPER Jan. 24, 1956 J, E. LYNAM ET AL 2,731,818

CAM MECHANISM OF KNITTING MACHINES Filed March 4, 1952 3 Sheets-Sheet 5Inventors: Tor-m EDWARD Lwvmq PoMERoy CooPER CAM MECHANISM or KNITTINGMACHINES John Edward Lynam, Nottingham, and Basil Pomeroy Cooper,Loughborough, England, assignors to William Cotton Limited,Loughborough, England Application March 4, 1952, Serial No. 274,758

Claims priority, application Great Britain March 5, 1951 9 Claims. (Cl.66-82) This invention concerns knitting machines and cam operatedmechanism therein. In knitting machines, particularly Cottons patent andother straight bar knitting machines, it is customary to operate certaindevices each by mechanism comprising a rotary cam and a truck levercarrying a truck or cam follower engaging said cam, and to cause thetruck to press against the cam and to follow its contours by means of areturn spring extending between the lever and a fixed anchorage.Particularly, in straight bar knitting machines the devices (e. g. theneedle bar or catch bar) to be moved have considerable inertia and sincea spring has to move its device while the follower is descending theflank of the cam the spring needs to be very strong. It thereforefollows that the strong spring throws a considerable load on the machinewhile the follower is ascending a flank of the cam, and since at oneperiod the spring pressure assists rotation of the cam and at anotherresists it the torque required to drive the cam fluctuates heavily witha consequent detriment to smooth running of the machine. Further, it isdifiicult to turn the machine by hand and to stop at a given stage, forthe spring pressure will often cause the machine to run backward orforward from said stage.

,An object of this invention is a construction which eliminates ormitigates these disadvantages. While the invention is chiefly applicableto straight bar knitting machines it is to be understood that it isapplicable to other knitting machines also, such for example as warpknitting machines.

The invention provides a knitting machine having cam mechanism foractuating parts of the machine comprising at least one pair ofcomplementary cams coupled together to rotate in unison about thesubstantially parallel axes, and cam follower means comprising truckmeans rotatable about a single axis between and parallel to the cam axesand closely constrained by the peripheries of the cams so as to bepositively displaced thereby in opposite directions transversely betweenthe cam axes. By complementary cams-there is meant cams the contours ofwhich are so formed (having regard to the relative speeds of rotation ofthe two cams) that one cam produces movement of the follower means inone direction .and the other cam produces movement in the reversedirection. It will, therefore, be appreciated that a cam mechanismaccording to this invention may dispense with a return spring such ashas hitherto been used, although if desired a light spring may beemployed to bias the cam follower means against one of the cams.

The contours of the cams are desirably so designed that at each regionwhere inertia force tends to cause the follower means to deviate fromits designed movements as predetermined by the contour of one cam, thistendency is corrected by the contour of the other cam. (Such inertia2,73 1,818 Patented Jan. 24,. 19 56 force may be due to the mass of themoving parts, or to the mass thereof together with acceleration ordeceleration called for by the contour of one cam.) To achieve thisresult the cams may be so formed that the follower means is at all timesclosely constrained between the peripheries of the cams. That is to sayeach crest on either cam is matched by a hollow on the other cam, andeach rise or fall on either cam is matched on the other cam by a fall orrise as the case may be.

The two cams preferably, but not necessarily, rotate in the samedirection.

The cam follower means may be constituted by a single follower such forexample as a truck or roller, opposite portions of which are engaged bythe two cams. Alternatively, if the cams are staggered there may be onefollower engaged by one cam and another follower engaged by the other.The follower means is preferably mounted on a single lever, e. g. onethe general length of which is substantially normal to a planecontaining the axes of the two cams. Alternatively, there may be twolevers which are coupled together, particularly if the cams arestaggered.

In the application of this invention to a Cottons patent or otherstraight bar knitting machine, two substantially horizontal cam shaftsare employed, these cam shafts being coupled together to rotate in thesame direction. Certain of the heavy duty cams (and notably that whichproduces the movements of the needle bar, both up and down and towardsand away from the pressers, and that which moves the catch bar to andfro to advance the dividing sinkers, and to retract all sinkers) aremounted at suitably spaced locations on what is, for convenience, calledthe main cam shaft. Each of these cams has its counterpart orcomplementary cam on the other cam shaft which for convenience will beregarded as the counter cam shaft. For each pair of cams, there is alever which extends in a direction which is substantially normal to'theplane containing the axes of the two shafts and carries a truck which isdisposed between the two cams, so that the latter act on twodiametrically opposed parts of the truck periphery. Each counter partcam is so formed that the associating truck is at all times closelyconfined between the peripheries of the two cams. Therefore, each pairof cams imparts positive movements in both directions to the associatedtruck and truck lever, although if desired a light spring may beprovided for biasing the truck against the main cam.

Both cam shafts are arranged to be shogged when it is desired to modifymovement of the parts which they operate, as for example when themachine goes into a fashioning motion. For this purpose, alongside eachcam there is either a plain cam or a further cam designed to produce themodified movements.

Certain of the light duty cams, such for example as also within thescope of the invention to provide some of the main cams on one shaft andothers of the main' cams on the other shaft, so that each shaft carriessome of the main cams and some of the counter cams.

Best results are obtained if the driving connections between the two camshafts are so arranged that there is little or no back lash, so that thetwo cams of a pair cannot get out of phase with one another. It is alsopreferred that the axes of the two cams and truck shall lie insubstantially the same plane.

In addition to the positive movement in both directions which isprovided by mechanism according to this invention, a further advantageis that if the cams of a pair rotate in the same direction the truckwill roll on the periphery of each of them with a minimum of slipping.

"Ihe above and other features of the invention are set forth in theappended claims and are disclosed in the detailed description given byway of example of the particular embodiments illustrated in theaccompanying drawings in which Figure I is a general sectional view of aCottons patent knitting machine according to the invention.

Figure 2 is a detail view of cams for needle bar raising and loweringmovement.

'Figure 3 is a detail view of cams for catch bar movements.

Figure 4 is a detail view of cams for needle bar forward and rearwardmovement.

Figure 5 is a detail of drive and shogging means for cam shafts.

Figure 6 is a plan view of a modification.

Referring now to Figure 1 the Cottons patent straight bar knittingmachine shown employs conventional needles 1, sinkers 2, knocking-overbits 3, and jack springs 6 which are operated from cams on cam shafts 4,5. The jack springs 6 are conveniently operated by conventional cam 7 oncam shaft 5 through the medium of truck arm 8, the knocking-over bits 3are conveniently operated from conventional cams 9 and 9a on shaft 5through the medium of truck levers 10 and 10a and the catch bar raisingand lowering is conveniently effected by conventional cam 11 on cam 5through the medium of truck lever 12.

However, the needle bar raising and lowering movements, needle barforward and rearward movements, and the catch bar forward and rearwardmovements are each effected by a pair of cams coupled together about thesubstantially parallel axes of the cam shafts 4 and 5 by one of eachpair being on the shaft 4 and the other of each pair being on shaft 5 atan opposite location and complementary to the first of the pair, and camfollower means comprising a truck lever for each pair of cams isdisposed with its truck between the appropriate cams so as to berotatable about a single axis between and parallel to the cam axes andclosely constrained by the periphcries of the cams so as to bepositively displaced thereby in opposite directions transversely betweenthe cam axes. Preferably as shown the trucks are disposed on an axissubstantially in the same plane as that containing the cam axes. Morespecifically, cam 13 (Figure 2) on shaft 5 is of conventional type forneedle bar raising and lowering movements, and cam 14 on shaft 4 is:complementary (and of dissimilar shape) to cam 13 i. e. rises and fallson cam 14 are opposite to those on cam 13 so that like movements aregiven to the truck 15 of truck lever 16 by both cams. Similarly as shownin Figure 3, cam 17 on shaft 5 is of conventional form for the catch barforward and rearward movement and cam 18 on shaft 4 is complementary(and of dissimilar shape) to cam 17 for operating on truck 19 of truckarm 20; Figure 4 shows that cam 21 on shaft 4 is of conventional typefor needle bar forward and reverse movement and cam 22 on shaft 5 iscomplementary (and of dissimilar shape) to cam 21 for operating on truck23 of truck arm 24.

Lever mechanism connecting truck arm 20 to the catch mechanism 25 forsinkers 2 may be conventional as shown, but truck arm 16 has a variableconnection with needle bar 26 to allow for maintaining the needles downat desired times such for example as when passing a thread carrieracross the needles without knitting say for a yarn change, or duringwelt forming or at other desired times.

For this purpose the arm 16 is free on shaft 27 and fixed on said shaftthere is the conventional arm 28 attached to the needle bar 26 and acoupling arm 29. This coupling arm 29 is connected to the truck arm 16by toggle links 30 and the centre pin 31 thereof is adapted to ride in aslot 32 in'a truck lever 33. This lever 33 has a truck 34 which normallyrides on a circular cam disc 35 on shaft 4 such as to maintain thetoggle rigid thereby transmitting movements of truck lever 16 to theneedle bar to effect normal movements of the needle bar. When however itis desired to maintain the needles down as aforesaid, truck 34 isshogged by shogging means 36 onto a second cam 37 and this cam 37 is soshaped that it moves the truck lever 33 and varies the height positionof slot 32, this in turn raises and lowers pin 31 so as to vary thesetting of the toggle links, and this variation constitutes variation ofleverage between the truck lever 16 and the needle bar 26 such thatmovements of the truck lever 16 by cams 13 and 14 are canceled out i. e.not transmitted to the needle bar which is consequently held in alowered position as desired.

Conventional means for varying the quality or stitch size of the fabricloops consists of arm 38 which is adjustable from pattern mechanism (notshown) to adjust the extent of forwards and rearwards motion of theneedle bar by limiting the distance of movement of peg 39. To permit theadjustment, cams 21 and 22 may be relieved say as indicated at 40 and inFigure 4. There may be a light spring 41 for biasing the truck of lever24 towards cam 21.

Figure 5 illustrates that the cam shafts 4 and 5 may be driven in thesame direction from a motor 42, through chain drive 43, and gears 44,45, 46. Means are preferably provided for preventing back lash such forexample as plate gears 47, 48 fixed on gears 45, 46 respectively andwhich are circumferentially adjustable to ensure close connection of thegear teeth.

Said Figure 5 also illustrates a form of shogging means comprising afork lever 49 engaging shaft 4 pivotally coupled to a fork 50 engagingshaft 5 so that the two shafts may be shogged by common shoggingmechanism operating on shaft 5 (not shown). Alternatively the shafts maybe shogged by separate mechanism one for each shaft.

As illustrated, each of the trucks 15, 19 and 23 is preferably mountedon a single lever the general length of which is substantially normal tothe plane containing the axes of the two cams operating it. Figure 6indicates that any pair of complementary cams may have its camsstaggered along the parallel axes of the shafts 4 and 5, there being aseparate truck for each cam of a pair, and the two tmcks being spacedalong the aforesaid single axis between and parallel to the cam axes andcoupled together for operation in unison.

We claim:

1'. A knitting machine having cam mechanism for actuating parts of themachine comprising at least one pair of complementary cams coupledtogether to rotate in unison about substantially parallel axes, and camfollower means comprising truck means rotatable about a single axisbetween and parallel to the cam axes and closely constrained by theperipheries of the cams so as to be positively displaced thereby inopposite directions transversely between the cam axes.

, 2. A knitting machine according to claim 1 having the cam followermeans disposed on an axis substantially in the same plane as thatjoining the cam axes.

3. A knitting machine according to claim 1 having the cams of dissimilarshape.

4. A. knitting machine according to claim 3 being a Cottons patent orother straight bar knitting machine.

5. A knitting machine according to claim 1 having means for rotating thecams in the same direction.

6. A knitting machine according to claim 1 having the cam follower meansconstituted by a single truck and the cams opposed.

2,781,818 5 a 6 I 7. A knitting machine according to claim 1 having thebiasing the cam follower means onto at least one of the cams staggeredalong the parallel axes and a separate cams. truck for each cam, the twotrucks being spaced along the single axis and coupled together foroperation in References Cited in the file of this Patent kntf h. t 1 1 h5 UNITED STATES PATENTS 1 ing mac me accor mg 0 c alm avmg a singlelever the general length of which is substantially 1165478 wmkler 1915normal to a plane containing the axes of the two cams, FOREIGN PATENTSand the cam follower means is mounted on the said lever. 11982 GreatBritain f 1847 9. A machine according to claim 1 having spring means 10

